The invention relates to a windshield wiping device, specifically for windows of automobiles, with a driveable wiper arm, with a wiper blade located on the wiper arm and configured as a flat blade, where the wiper blade comprises a wiper rubber with a receiver for the support element and a support element located in the receiver configured as a pressure-distributing flexible spline, with a wiper lip positioned on the wiper rubber abutting the glass to be wiped.
In a wiping device of this type, known for example from DE 197 34 843A1, the support element, for example in the form of one or two ribbon-like elongate flexible splines, ensures optimal distribution of the contact pressure exerted by the wiper arm against the glass to be wiped. To achieve this, the support element is correspondingly pre-curved in the unloaded state, when the wiper blade is not abutting the glass, and manifests a curvature. The support element of a wiper device of this type thus replaces the complicated yoke construction with several yokes and claws, such as is known from DE 1 505 357 A1 for example.
In known wiping devices which have an aforementioned yoke construction, load-alleviating means are known which relieve the load on the wiper lip in a parked position and preferably lift the wiper lip away from the glass to be wiped (DE 30 34 051 C3). With this type of wiping device, the load-alleviating means include a cam located on the wiper arm which rides up on a ramp on the glass or in the region around the glass. This achieves alleviation of the load and advantageously lifts the wiper lip from the glass to be wiped
Such load-alleviating means are, however, not suitable for wiper devices of the type described initially, which have a pre-curved support element. Lifting the wiper lip from the glass to be wiped is not possible in a straightforward manner as a consequence of the pre-curving of the support element. To make it possible to lift the wiper lip in accordance with the prior art, a height difference of about 100 mm would have to be overcome when the lip rides up on the ramp.
The object of the present invention is therefore to prepare a wiper device without a yoke and claw construction, in which load-alleviating means are provided which relieve the load on the wiper lip when the wiper device is in a parked position and preferably lift the lip from the glass to be wiped.
This object is achieved in the case of a wiper device of the type described above in accordance with the invention, in which the load-alleviating means comprise two cams spaced at a distance to each other on the support element configured as a flexible spline and ramps located on the glass or in the region of the glass coacting with the cams, where the cams, when in the parked position, ride up on the ramps to relieve the load on the wiper lip.
The particular advantage of a wiper device of this type is that as a result of the cams riding up on the ramps to lift the wiper lip from the glass to be wiped, a height difference of only a few millimeters has to be overcome when the cams provided are spaced at a suitable distance. The number of cams to be employed is dependent on the pre-curvature of the at least one support element as well as on the length of the wiper blade in the longitudinal direction. Advantageously as a result more than two cams, for example, three, four or five cams can be used in accordance with the invention. The position of the cams is selected in accordance with the invention such that the result is an equal relief of the load along the entire length of the wiper rubber.
The cams and the ramps can advantageously be of a plastic material. When the wiper arm is articulated centrally on the wiper arm, and with a dissymmetrical pre-curvature of the support element around the center of the wiper blade, the cams are advantageously disposed symmetrically on the right and left adjacent the center of the wiper blade. The cams are advantageously located on side of the wiper blade facing the ramps. In addition, if only two cams and two ramps are employed, it is recommended to place them in each case at about one quarter of the extended length of the support element in accordance with a further improvement to the invention.
In a particularly advantageous aspect of the invention, the ramps comprise an ascending section running at an angle to the surface of the glass and a parking section preferably running largely parallel to the surface of the glass. When the cams rest on the parking section, the cams and thus the wiper blade do not back slide along the ascending section onto the glass to be wiped. To prevent any undesirable movement of the cams from the parking section, indents or depressions can be furnished in the parking sections in which the cams are held in the parked position.
Advantageous provision can be made under the invention for the support element to have recesses to position and retain the cams against the support element. It is conceivable, for example, that the cams are of plastics material and can be snapped onto the support element by means of latching elements. On the other hand, it is also conceivable that the cams are molded or cast in one piece directly onto the recesses in the support element.
In another particularly preferred aspect of the invention, the area of the wiper rubber away from the glass surface has a spoiler-like rise. The contact pressure of the wiper blade against the glass surface to be wiped is increased particularly at high vehicle speeds.
In accordance with the invention, the cams each include a securing section surrounding the area of the wiper blade facing away from the glass. A securing section of this type has the advantage that the cams can be attached extremely solidly to the wiper blade providing operating reliability.
In a particularly preferred aspect of the invention, the wiper rubber includes two longitudinal grooves arranged opposite each other extending in the longitudinal direction as receivers for the support element and a support element in the form of two ribbon-like, elongate flexible splines positioned in the longitudinal grooves. A wiper blade of this type has proven to be particularly advantageous, particularly in practice. Advantageous provision can be made here for the securing section to surround and/or engage the longitudinal sides of the flexible splines facing away from each other from beneath. This ensures a reliable attachment of the cams to a wiper device which has two flexible splines. Additionally, the sections engaging the flexible splines from beneath can be retained to the flexible splines through a snap fit.
An improvement to the invention, under which the cams and the ramps are furnished with mutually repelling magnets or are configured as mutually repelling magnets, has the advantage that the cams can slide contact-free or virtually contact-free onto the ramps, which avoids unwanted noise.